Method of releasing the pressure of mixtures of solids and liquids existing under high pressure



Aug. 21, 1934. w. R. TATE El AL 1,970,371

' METHOD OF RELEASING THE PRESSURE 0F MIXTURES 0F SOLIDS AND LIQUIDS EXISTING UNDER HIGH PRESSURE Filed April 19, 1930 Patented Aug. 21, 1934 ITED STATES METHOD OF RELEASING THE PRESSURE F MIXTURES or SOLIDS AND LIQUIDS ExIs'rrNG UNDER HIGH PRESSURE William RonaldTate, Harold Park Stephenson, and Harry Pitt"Dean, Norton-on-Tees, England, assignors to Imperial 'Ghemical lndustries' Limited, London, England, a British company Application April 19, msofser al No. 445,814

In Great Britain May'9, 1929 '1 Claims. (or. 196- 53) This invention relates to a method of releasing the pressure of mixtures of solids and liquids existing at high pressures, and t the principal object is to provide a system whereby the wear and tear on reducing valves is avoided. Particularly when a solid of abrasive character, such as iron oxide, is present in the mixture the consequential erosion of valve parts is a very serious matter. The invention is especially applicable 1. to the release of pressure on mixtures of powdered coal and oil from a destructive hydrogena:

tion process, with or without other solid materials of an inert or catalytic character. A subsidiary object of the invention is to provide a system whereby a large proportion of the potential energy of the high-pressure mixture is recovered as useful external work.

According to the invention, the pressure of the liquid-solid mixture is transferred to a fluid,

preferably a liquid, whose pressure can then be released in anyknown manner without difliculty since erosion does not occur to such a serious extent in absence of solid matter. The transfer of pressure can be effected by the aid 5 of slowly moving parts or without the necessity of constricted passages liable to erosion.

In the preferred form of the invention the pressure on the mixture is released in a cylinder ram the piston of which is balanced by the g pressure of an auxiliary liquid such as water or oil contained in a second cylinder, the admission and exhaust of mixture and auxiliary liquid respectively being controlled to ensure a slow movement. The mixture from which the pressure has been released is then expelled from the cylinder of the ram by the return stroke of the piston.

The invention is illustrated in the accompanying diagram. In the figure a mixture of solid .40 and liquid is withdrawn from a high-pressure vessel 1 and it is required to release the pressure on the mixture. The mixture is allowed to pass through a pipe 2 to the cylinder 4 of the ram 5. The piston 6 of the ram acts also in the cylinder 11 of a second ram 10, and reciprocates between the two rams in accordance with the positions of the valves3, 7, 12 and 13, which control the inlet and outlet of mixture and of auxiliary fluid to the respective cylinders. These .50 valves except valve 3 open and close only when the piston 6 is stationary, i. e. when there is no movement of mixture or of liquid through the connecting pipes. The valve controller may be of the type described in British specification No. 282,505 in which cams on a timing shaft actuate periodically pilo t i alves. The ram may convenientlybe of greater area in the auxiliary liquid cylinder as shown.

The exit pipe 8 for mixture-leads to a low pressure storage vessel 9. The inlet pipe 15 for auxiliary liquid 1. e. liquid to which the pressure is transferred is supplied with liquid at a few atmospheres pressure by the accumulator, 14 of the ordinary Weight loaded type and pump 18. The exit pipe 16 for auxiliary liquid is provided with a variable orifice 17 to control the outlet of liquidand hence the rate of movement of the piston 6 and the rate of admission of mixture into the cylinder 4. Theauxiliary liquid at high pressure passes to the accumulator 19 and is utilized in any known manner for the recovery of its energy; its pressure can be released without inconvenience as it contains no solid matter, for example in the motor 20.

The working-of the system is as follows. The piston 6 beinggat the top of its stroke, the valve 7 is shut and the valve 3 opened. Simultaneously valve 12 is shut and valve 13 opened, and the pressure of the mixture in the cylinder 4 will cause the piston to fall and expel the auxiliary liquid through the orifice 1'7 and the pipe 16. Valve 3 is preferably shut before the piston has reached the opposite limit of its stroke so that the latter part of the stroke acts to release the pressure in the cylinder 4 before valve 7 opens. This happens partly because of the extremely high pressure, 200 atmospheres or over and partly because the gas dissolved in the liquid makes its escape on releasing the pressure. Then the valve 13 is shut and valve 12 opened and auxiliary liquid admitted to the cylinder 11 to cause the piston. to expel the contents of the cylinder 4 (now at low pressure) into the container 9. The cycle is then repeated.

The valves 3, 7, l2 and 13 are preferably operated hydraulically by an independent system and in any case their movements may be co-ordinated through the agency of a timing gear in known manner.

Cylinders may be also inverted, the auxiliary fluid cylinder on top.

The arrangement shown however, has the advantage that any. gas dissolved in the liquid portion of the material and liberated on reduction of pressure will rise in the cylinder 4 and make its escape to the container 9 before the liquid is pushed out by the return stroke of the piston.

We declare that what We claim is 1. A process for obtaining a mixture of solid 110 and liquid at substantially atmospheric pressure from a mixture of the same ingredients at high pressure, said high-pressure mixture being the product of a high pressure chemical reaction, consisting in introducing the said mixture without substantial pressure drop into a space,

and then allowing it to expand; therein j byi transference of its pressure energy to a non-' 7 in passing a non-abrasive auxiliary liquid into 2. A process for obtaining a mixture of solid abrasive auxiliary liquid.

and liquid at substantially atmospheric pressure from a mixture of solid andliquidat high consisting in filling a confined space with-a none pressure drop into a second confined space,

transferring the pressure from said mixture. to'

on said auxiliary liquid. V

3. A process as set forth in. claim 6 in which the expulsion of the said material is efiected by supplying said auxiliary liquid at a few atmospheres pressure, to the" said first confined space. v I

4. A process as set forth in claim 6 in which the expulsion of the said-material is effected by supplying said auxiliary liquid; at a few atmospheres pressure, to the said first confined space and so regulating the rates of supply'and expulsion of said liquid that only slow movement occurs. Y 5, A process for obtaining a mixture of solid said auxiliary liquid and releasing the pressure and liquid at substantially atmospheric pressure from a'mixture of solid and liquid at'high pressure, said high-pressure mixture being the'prod uct of a high pressure chemical reaction, 'consisting in passing said mixture-into a confined space without substantial pressure drop, transferring the pressure to a non-abrasive auxiliary g 6. A process for obtaining a mixture of solidand liquid at substantially atmospheric pressure from a mixture of high pressure solid and liquid,

said high-pressure mixture being the ;product of'a high pressure chemical reaction, consisting and therebyexpanding a variable space, hereinafter termed the first space, which space is complementary to another variable space, hereinpressure, said high-pressure mixture being the, product of a high pressuretchem'ical reaction,

after termed,[the second space, introducing the mixture of high pressure liquid and solid withxout substantial pressure drop into the second abrasive auxiliary liquid, allowing the mixture of solid and liquid to flow without substantial space thereby slowly expanding it and slowly contractingthe first'space and ejecting a part of the non-abrasive liquid therefrom, arresting the-inflow. of the liquid and solid into the sec- 04nd space, allowing the liquid and solid therein to drop to substantially atmospheric pressure by further expansion-of the second space, and finally ejecting the liquid and solid from the second space by expanding the first space by passing thereinto non-abrasive liquid.

-7. A process for obtaining a mixture of solid and liquid at substantially atmospheric pressure from a mixture of high pressure solid and liquid, said high-pressure mixture being the product of a high pressurechemical reaction, consisting in passing the said material without substantial pressure drop into and thereby expanding a variable space, arrestingthe inflow of the "material into the space, allowing the material therein to drop to substantially at mospheric pressure by further expansion of the space, and finallye'jecting the liquid and solid therefrom by contracting the space.

WILLIAM RONALD TATE.

HAROLD PARK STEPHENSON; HARRY PITT DEAN. 

